JPH06281995A - Exposure control device and camera - Google Patents

Abstract

(57) [Summary] [Object] To provide an exposure control device capable of detecting the position of a light-shielding blade with high accuracy without increasing the size of the light-shielding blade. [Structure] Three light-shielding blades (sectors) 11, 12, 13
Among them, a magnetic part 11a in which a plurality of N poles and S poles are alternately arranged is formed by a magnetic plating method in a part of the sector 11, and the magnetic part 11 with the movement of the sector 11 by the Hall element 14 is formed.
The passage amount of a is detected, and the opening amount formed by the sectors 11 to 13 can be detected.
The magnetic part can be arranged without being restricted by the position of, and the Hall element 14 can be arranged without being affected by the positions of the sectors 12 and 13, and the exposure control device can be miniaturized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure control device using a light-shielding blade in an optical device such as a camera or a video camera, and a camera provided with the exposure control device using the light-shielding blade.

[0002]

2. Description of the Related Art In an exposure control device such as a shutter and a diaphragm having light-shielding blades that form an aperture of a camera, the amount of the aperture is detected and used as a signal of a light emission timing at the time of flash photography, or at the time of daylight photography. A control method used as a shutter close command signal for exposure control in (1) is known.

The following has been proposed as a method for detecting the opening amount of a light shielding blade (hereinafter referred to as a sector).

(1) A direct detection system in which a plurality of slits are formed in a part of the sector and the slits are detected by a photosensor to detect the position of the sector.

(2) An indirect detection method in which the movement of a member that drives a sector is detected by a photosensor, an electrical section, or the like.

[0006]

However, the direct detection method (1) has the following drawbacks.

Since the slit must be set so as to always operate in a portion other than the opening, the sector becomes large, which deteriorates the operating performance of the sector and hinders downsizing of the exposure control device.

FIG. 10 shows an exposure control device of a direct detection system using a slit, 1 is an opening, 2 is a first sector rotatably attached to a main plate (not shown) by a spindle 2a,
The first sector 2 has a plurality of slits 2b outside the opening 1.
Is provided. A second sector 3 is rotatably attached to a base plate (not shown) by a support shaft 3b. Reference numeral 4 denotes a drive pin, which is a long groove 2c of the first sector 2 and a long groove 3 of the second sector 3.
By slidably fitting with b and moving in the direction of arrow A and its opposite direction by a known mechanism, the first sector 2 and the second sector 2
The sector 3 is driven integrally, and the notch 2d and the notch 3
It is designed to open or close with c. 5
Is a photo sensor attached to a ground plate (not shown), detects the slit 2b of the first sector 2, and detects the position or movement amount of the first sector 2.

As described above, the slit 2b is provided at a position which always operates outside the opening 1 so as not to affect the opening shape of the sector, and therefore the first sector 2 becomes large. ing. Therefore, the miniaturization of the entire unit is hindered.

Further, since the pitch and size of the slits 2b cannot be made so small in manufacturing, it is impossible to detect the fine movement of the sector.

The indirect detection method (2) has the following drawbacks.

In this system, in FIG. 8, the movement of the drive pin 4 or a member that moves integrally with the drive pin 4 is detected, but generally the drive pin 4 has a smaller amount of movement than a sector. Therefore, it is difficult to detect the movement in detail, and if there is looseness in the engagement with the sector, an error occurs between the opening amount of the sector and the position of the drive pin 4, and the opening amount of the sector is accurately determined. Difficult to detect.

[0014]

Although the direct detection method for detecting the opening amount of a sector has a higher detection accuracy than the indirect detection method, since a slit is provided in the sector which is a light shielding member, the position where the slit is formed. Has to be provided outside the opening, which causes an increase in the size of the exposure control device, which in turn hinders the size reduction of the camera.

SUMMARY OF THE INVENTION It is an object of the present invention to solve such conventional problems and to provide an exposure control device and a camera that can maximize the advantages of the direct detection method and do not increase the size.

[0016]

1 to 3 show a first embodiment of the present invention.

In this embodiment, the opening amount of the opening 1 is controlled by the three sectors of the first sector 11, the second sector 12, and the third sector 13, and the support shafts 11 are provided on the main plate (not shown).
Since the b, 12b, and 13b are pivotally supported, the sectors 11 to 13 are rotatable about the pivots 11b to 13b as fulcrums. In addition, the long grooves 11c formed in the first sector 11, the second sector 12, and the third sector,
Drive pins 4 similar to those of the conventional example shown in FIG. 10 are slidably fitted to 12c and 13c, and each sector 11 to 13 is rotated by the movement of each drive pin 4 in a predetermined direction. . The drive pins 4 are integrally driven by a known drive mechanism.

In this embodiment, as shown in FIG. 1, the first sector 11 has a magnetic portion in which a plurality of "N poles" and "S poles" are alternately arranged in a part of the sector body formed of a light shielding member. 11a is formed. And this magnetic part 11
A Hall element 14 is attached to a ground plate (not shown) as a sensor means of the magnetic portion 11a in accordance with the movement locus of a, and the passage of the magnetic portion 11a accompanying the movement of the first sector 11 is detected to detect the first to third sectors. It becomes possible to detect the opening amount.

The magnetic portion 11a is formed by, for example, a known magnetic plating method, and this plating method is based on "Development of magnetic material and high dispersion of magnetic powder" issued by General Technology Center Co., Ltd.
2, which will be briefly described with reference to FIG. 2, both surfaces of the base material B of the sector are plated with Ni, and then Co—P plating, which is magnetic plating, is applied to the surface of the Ni plated layer. If necessary, the surface of the Co-P plated layer can be coated with a matte coating.

That is, the photosensor 5 which is the detecting means in the conventional example shown in FIG. 8 cannot be arranged at least at the position where the sector 3 passes, but the Hall element 14 which is the detecting means in this embodiment is the second element. Sector 1
2. Since it is not affected by the operation of the third and third sectors 13, it can be arranged anywhere as long as the magnetic portion 11a passes, and the degree of freedom of layout is widened. Also, since the Hall element is insensitive to the change in the gap with the magnetic portion 11a,
There is an advantage that the detection accuracy does not deteriorate even if the sector flaps.

Further, in the conventional example shown in FIG. 10, the detection slit 2b had to be provided outside the opening 1 at a position where it always operates, but the magnetic portion 11a in this embodiment has an opening shape. Because it will not affect
Since it may be provided anywhere in the first sector 11, it does not cause an increase in the size of the sector as in the conventional case.

Therefore, the exposure control device can be made compact, and the camera can be made compact. Here, the plating conditions and characteristics of the magnetic plating will be described below.

As described above, the base material B of the sector is Ni-plated and then Co-P plated.
FIG. 4 shows the relationship between the i plating thickness and the signal output of the Hall element 14.

FIG. 4 shows the relationship between the gap and the output due to the difference in the Ni plating thickness, and it can be seen that the output increases when the Ni plating layer is thickened. However, the thicker the plating, the longer the plating time, which causes problems in terms of cost and productivity, increases the inertia of the sector, and adversely affects the driving surface. Therefore, the Ni plating thickness on one side should be 50 μm or less. It is good to set an appropriate value.

On the other hand, consider the Co-P plating thickness and the signal output. As a general tendency, the maximum magnetic flux density (the magnetic flux density on the Co-P plating surface) does not change much depending on the plating thickness.
Therefore, for the same reason as the above Ni plating, it is desirable to set the Co-P plating thickness on one side to an appropriate value of 50 μm or less.

FIG. 5 shows a second embodiment of the present invention.

This embodiment is different from the first embodiment shown in FIG. 1 in that "N" of the magnetic portion 11d formed in the first sector 11 is changed.
The pitch between the “pole” and the “S pole” is made narrower as shown in FIG. 6, and the MR element 21 is used as a sensor to detect the passage of the magnetic portion 11d accompanying the movement of the first sector 11. 6A shows the magnetic portion 11a in the first embodiment, and FIG. 6B shows the magnetic portion 11d in the present embodiment.

In this embodiment, the MR element 21 is not affected by the operations of the second sector 12 and the third sector 13 as in the case of using the Hall element 14 of the first embodiment described above.
It may be arranged anywhere as long as the magnetic portion 11d passes, and the degree of freedom of layout is widened. Also, the magnetic part 11d
Since it does not affect the opening shape at all, it can be provided anywhere in the first sector 11, and therefore there is no increase in the size of the sector as in the conventional example of FIG.

Further, the Hall element 14 in the first embodiment.
The pitch between the north and south poles of the magnetic part 11a that can detect
Since it is m or more, it is suitable for a camera that does not require fine control, but since the pitch between the N pole and the S pole of the magnetic part 11d that can be detected by the MR element 21 used in this embodiment is 0.1 mm or more, fine control is required. It can also be used for various cameras. In the related art, the aperture amount is controlled by outputting a blade closing signal after a lapse of a certain time after the photosensor signal is input. However, in the detection method using the MR element 21, the position and pattern of the magnetic portion 11d are controlled. With proper setting, the aperture can be controlled only by inputting the MR signal.

FIG. 7 shows a block diagram for controlling the aperture by inputting the MR signal, and FIG. 8 shows a diagram of the MR signal and the aperture waveform.

In FIG. 7, reference numeral 22 denotes a magnetic detection circuit, M
A voltage is applied to the R element 21 or the output voltage of the MR element 21 is applied to a comparator to generate a pulse-shaped M as shown in FIG.
It includes circuitry to form the R signal. 23 is a drive pin 4
Is a drive control circuit for controlling the drive mechanism of, and 24 is a control circuit for controlling the exposure control device.

FIG. 8 shows the MR signal and opening waveform when each sector is fully opened. The MR signal of several pulses is obtained from the magnetic detection circuit 22 from the opening start to the end of each sector (xy section). You can see that That is, the number of pulses of this MR signal is counted by a known technique, and based on the aperture value obtained by the distance measuring means of the camera (not shown), the MR signal having the count number corresponding to the aperture value is obtained. ,
When a close signal is sent from the control circuit 24 to the drive control circuit 23, the drive pin 4 is driven in the closing direction and each sector is closed. As described above, the aperture control can be performed only by inputting the MR signal.

Not only the MR signal but also a well-known method may be used to send a closing signal to the drive control circuit 23 after a predetermined time has elapsed from the input of the MR signal to control the aperture.

Needless to say, even if the Hall element 14 is used in place of the MR element 21, the aperture can be controlled just by inputting the Hall signal.

As described above, in this embodiment, it is possible to provide a compact exposure control device capable of fine control by combining the magnetic plating and the MR element.

FIG. 9 shows a third embodiment of the present invention.

This embodiment is similar to the first and second embodiments in that
Although the opening amount is controlled by one sector, the first sector 31 itself is made of a permanent magnet material. Specifically, after the permanent magnet material is rolled to have an appropriate thickness, it is punched into a predetermined shape, and a plurality of "N poles" and "S poles" are alternately magnetized at a constant pitch at a suitable position. The part 31a is formed. Then, the magnetized portion 31a is detected by the MR element 21 as in the second embodiment.

According to this embodiment, the same effects as those of the above-described embodiments can be obtained, and the camera can be downsized.

In the first and second embodiments described above, the recording information of the magnetic portion provided in the first sector 11 is the N pole and the S pole, but the information is not limited to this and other information is also possible. May be

Further, the number of sectors of the light shielding member is not limited to the above-mentioned embodiment, and may be two or more.

[0041]

As described above, according to the present invention,
The light-shielding blade can be provided with a means for detecting the position of the light-shielding blade without being limited to the opening position, and the light-shielding blade can be downsized and the exposure control device can be downsized accordingly. In addition, the degree of freedom in the layout of the detection elements for detecting the position of the light-shielding blade is increased, which also makes it possible to make the exposure control device compact, and consequently to make the camera compact.

[Brief description of drawings]

FIG. 1 is a plan view of a first sector according to a first embodiment of the present invention.

FIG. 2 is a view showing a cross section of a magnetic part formed in the first sector of FIG.

FIG. 3 is a front view of the exposure control device according to the first embodiment.

FIG. 4 is a diagram showing a relationship between a plating condition of magnetic plating and output characteristics.

FIG. 5 is a front view of an exposure control device according to a second embodiment.

6A and 6B show pitch intervals of magnetic portions, FIG. 6A shows the magnetic portion of the first embodiment, and FIG. 6B shows the magnetic portion of the second embodiment.

FIG. 7 is a block diagram for controlling aperture by inputting an MR signal.

FIG. 8 is a diagram showing an MR signal and an aperture waveform.

FIG. 9 is a front view of an exposure control device according to a third embodiment.

FIG. 10 is a front view of a conventional exposure control device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Opening 4 ... Driving pin 11,112,13,31 ... Sector 11b, 12b, 13b, 31b ... Spindle 11c, 12c, 13c, 31c ... Long groove 11a, 11d, 31a ... Magnetic part 14 ... Hall element 21 ... MR element

Claims (9)

[Claims] 1. An exposure control device for controlling exposure by moving a plurality of light-shielding blades with respect to an opening, wherein at least one light-shielding blade of the plurality of light-shielding blades has position information recorded on a part thereof. An exposure control device in which the magnetic layer is formed, and the position of the light-shielding blade is detected by position information detection means for detecting the position information. 2. The exposure control device according to claim 1, wherein the magnetic layer is formed by a magnetic plating method. 3. The exposure control according to claim 2, wherein the magnetic layer is composed of a nickel plating layer formed on the base material of the light shielding blade and a cobalt plating layer formed on the nickel plating layer. apparatus. 4. The exposure control device according to claim 3, wherein the nickel plating layer is 50 μm or less on one side and the cobalt plating layer is 50 μm or less on one side. 5. An exposure control device for controlling exposure by moving a plurality of light-shielding blades with respect to an opening, wherein at least one light-shielding blade of the plurality of light-shielding blades is made of a magnetic material, and a part thereof is formed. An exposure control device, characterized in that an information recording section for recording position information is formed on the substrate, and the position of the light-shielding blade is detected by position information detecting means for detecting the position information. 6. The exposure control device according to claim 1 or 5, wherein the position information detecting means is an MR element. 7. The exposure control device according to claim 1, wherein the position information detecting means is a Hall element. 8. The exposure control device according to claim 6, wherein the aperture control is performed by counting the number of pulses of an input signal from the MR element or the Hall element. 9. A camera comprising the exposure control device according to claim 1. Description: